Web clickstream data are routinely collected to study how users browse the web or use a service. The ability to recognize and summarize user behavior patterns from such data is valuable to e-commerce companies. Clickstreams record user clicking actions on the web. Analyzing clickstream data provides insights into user behavior patterns, which are extremely valuable for e-commerce businesses. For example, knowing different user behavior patterns helps conduct market segmentations in order to develop marketing strategies, or enhance personalized shopping experience. In practice, however, learning the various user behavior patterns is nontrivial. Analysts often have little knowledge, but many questions, about what user behaviors are hidden in a clickstream dataset.